Rework mount detection for 6.0 API

In 6.0, the mounts API changed from the GetCompanionInfo("MOUNT") style
to the C_MountJournal:... style.  This commit uses the new style to
detect the mount types, then sets the flags on the mounts as if it were
still the 5.4 scheme.  There is no other change of consequence.  This
makes it work for me.

It also touches up the api version so it's no longer "out of date" as
far as the game is concerned.